The most accurate description of Arianna’s work is:
Arianna multiplied with the reciprocal of the dividend instead of the reciprocal of the divisor.
In her solution, she is supposed to divide \( \frac{2}{3} \) by \( \frac{4}{5} \), which means she should be multiplying \( \frac{2}{3} \) by the reciprocal of \( \frac{4}{5} \) (which is \( \frac{5}{4} \)). Instead, she multiplied \( \frac{2}{3} \) by \( \frac{4}{5} \), leading to an incorrect calculation.